You're on the right track, but going about the repair the wrong way. Even if you could identify a certain wire to test, we don't test them and we don't repair just one. Eventually every wire will break, then you'll be doing the job all over multiple times. All it takes is one strand of wire still intact for you to find continuity, but you'll never get enough current through that to run a window motor.
The way I handle this is to first pull the rubber boot back between the driver's door hinges, and look for a broken or frayed wire. When I see that, I start by pulling a little of the harness out of the "A" pillar so I can cut and splice in a section that was never flexing. Same for the door. This means taking the interior panel off so I can unplug connectors. That allows me to pull the harness out of the door a few inches and again, splice to solid sections.
Most often I find I need an 11"-piece of wire to replace the flexing section, but my secret is to splice in a 22"-piece for every wire. Colors don't matter, but you will want to use the same gauge for each one. Do just one at a time so you don't mix up any wires. Strip about 1/2" of insulation off each end of the original wire and both ends of the new piece. Slide the strands into each other, (no twisting like we do with house wiring), solder the first splice, press down any sharp points sticking up, then slide on a piece of moisture-proof heat-shrink tubing and heat it to seal the splice. Slide on the next piece of heat-shrink tubing, make the splice and solder it, then seal it with the heat-shrink tubing.
When all the wires are done, that section of harness will be twice as long as necessary. Push half of it into the "A" pillar and coil it where it won't catch on things like the parking brake pedal. This is a rather time-consuming job. The purpose of using twice the length of wire is if this repair has to be done again, just pull the extra out of the "A" pillar and you're half done.
On both ends, the splices should be pushed inside the door and the "A" pillar so they don't flex.
Given the age of your model, there's a good chance there's no computer involved in running the rear windows. To say that a different way, they still likely used common sense. If that is the case, it's important to understand there are actually eight sets of switch contacts in play with every passenger window. When no switch is pressed, both motor wires are grounded through both the driver's and the passenger's switch assembly. When either switch is pressed either way, that one contact moves away from ground and gets 12 volts applied to it. This very common arrangement is what lets them change polarity when there's only two wires going to the motor. This also means three sets of contacts are in use for ground, and those parts of the switches are released, when the motor is running, When you have one switch that doesn't work, particularly when it doesn't work in only one direction, either switch could be at fault. If you diagnose by the faster switch substitution method, you must try both switches. For the rear one, you can usually use the one from the other side. For the front one, it's different than the passenger's switch, so you might need to find one in a salvage yard. Once you know which one solves the problem, you can buy a new replacement if you want to.
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Monday, July 15th, 2024 AT 4:00 PM
